Transmitting-receiving circuit arrangement for short waves



p 25, 1950 A. VAN WEEL TRANSMITTING-RECEIVING CIRCUIT-ARRANGEMENT FOR SHORT WAVES Filed July 20, 1946 ADELBERT [547V T IZFEZZ INVENTOR.

AGE/VT Patented Apr. 25, 1950 sTA'rss ENT D'FFICE TRANSMITTING-RECEIVING (ZIBCUI-T ARRANGEMENT FOR SHORT WAVES ApplicationJuly 20, 1946, Serial No. 685,199 In the Netherlands .l'uly 23, 1943 Section 1, Public Law 690, August 8,1946 Patent expires July 23, 1963 7 Claims. I

This invention relates to a transmitting-receiv ingcircuit-arrangement for short waves, in which for the reception, use is made of two mixing systems, to whose input-electrodes the incoming oscillations are supplied in push-pull and the local oscillations in the same phase. This method of receiving has important advantages in transmitting ultra-high frequencies, as in this manner a smaller input damping and a more favourable signal-to-noise ratio is achieved.

Transmitting receiving circuit arrangements are known in which a tube acting as a local oscillator inthe case of reception is also used for'the generation of the oscillations to be transmitted. However, if for the reception use is made of two mixing systems arranged in push-pull in the aforesaid manner, application of this method entails difficulties, as the local oscillations generated in single phasemust in this case first be converted into oscillations being symmetrical with respect to earth, in order to make them suitable for transmission by means of a dipole aerial.

According to the invention, these diificulti'es are avoded by providing means perm tting the said mixing systems or a couple of high-frequency amplifying systems preceding them and arranged in push-pull to be coupled back in such a manner that these systems generate oscillations that are transmitted by means of a dipole aerial.

The circuit constituted by the series-connectlon of the impedances common to the input circuits of the two mixing systems with the network formed by the non-common portions of these input circuits jointly with the input impedance of the systems, which circuitwill be referred to hereinafter as the single-phase input circuit, is preferably tuned to the frequency of the local oscillations to be used'for the reception, means being provided to couple back the mixing systems in such a manner as to generate the local oscillations thesaid circuit. This yields the advantage that no separate oscillator tube is-required for the reception. Th circuit-arrangement in question may comprise one or more switches by means of which such feed-hack impedances and/or damping resistances may optionally be switched in as to generate either the. oscillations to be transmitted. or the local oscillations tobe used for the reception.

In order that the invention may be clearly a. (it) The figure representsa transmitting-receiving circuit-arrangement in which a dipole aerial D, D" is used both for the reception and for the transmission of. oscillations. When using it to constitute a receiving aerial the incoming oscillations are inductively transmitted by means of an aerial coupling coil L0 to an input resonant circuit consisting of two inductances L1" and Li" and a tuning condenser C1 and whichis arranged in push-pull between the control-grids of two mixing triodes T and T". The junction of coils Li and; L1" is earthed through a variable condenser C2 and connected through a resistance R1 toasource of potential (not represented) whichsupplies a suitable negative biasto the controlgrids of the triode'sT and T".

The cathodes of the triodes T and T" are jointly connected to earth through an inductance Lawhich is coupled'with a coil L3 included in the output circuit of a local oscillator O' which is represented diagrammatically. With the aid of the coil Lathe local oscillations are consequently supplied to the input circuits of the triodes by means of so-called cathodeinjection and this in such a manner that the local oscillations appear in the same phase on the control-grids of the two triodes.

A resonant circuit tuned to the intermediate frequency and consisting of two inductances Li and L4" and two condensers C4 and C" is connected in push-pull to the anodes of the two triodes. In series with the, coils L4 and L4" are connected high-frequency chokes L5 and L5" which serve to prevent the transmission of the incoming high-frequency oscillations to the receiver parts next to the mixing stage. The junction of coils L4 and L4" is connected through a condenser G5, which constitutes practically a short-circuit to the intermediate frequency oscillations, to earth and through a resistance R2 to the positive terminal of a source of anode potential. (not represented). Furthermore the coils L4 and L4" are coupled inductively with a second intermediate frequency circuit 116,116 from which the output voltage of the circuit is taken. The

junction of the condensers C4 and C4" is connected to the cathodes of the two triodes through impedances that will be described in detail hereinafter. In practice, the input resonant circuit L1, L1, C1 will frequently have the form of a Lecher system. Ihe triodes T and T" may advantageously be housed in one tube and, as the case may be, may have a cathode in common.

To supply as high as possible a voltage to the control-grids of the mixing triodes, the singles phase input circuit, which is constituted by the series-connection of the impedances (L2, C2) common to the input circuits of the two triode systems with the network constituted by the noncommon portions of these input circuits (L1', L1) jointly with the input capacities of the triode systems, is tuned to the frequency, which may, for instance, take place by adjustment of the condenscr C2.

According to the invention the anode circuits of the triodes T and T include inductances L7 and L7 which jointly with the anode controlgrid capacities of the triode systems produce such a feed-back that the triode systems generate oscillations which are symmetrical with respect to earth and are transmitted by the dipole aerial D, D". A modulation of these oscillations may, for example, be achieved by connecting a key S in series with the resistance R2.

The inductances L7 and L1" bring about a negative damping of the resonant circuit L1, L1, C1, which leads to the generation of the oscillations to be transmitted, and in addition a negative damping of the single-phase input circuit tuned to the oscillator frequency, due to which a single-phase oscillation might be generated in addition to the oscillations to be transmitted. To prevent this a condenser C7 is inserted in the connection common to the two tubes between the cathodes and the junction of the condensers C4 and C4", as a result of which the negative damping of the single-phase input circuit is removed again.

, When passing over to reception the coils L1 and L7" may be short-circuited by means of switches S1 and S1". A highly satisfactory construction consists in that by means of a switch S2 the condenser 07 is replaced at the same time by an inductance La, so that upon switching over negative damping of the single-phase input circuit occurs, as a result of wh ch the local oscillations required for the reception are generated in this circu t. The separate oscillator may than be omitted. Instead of alternately cutting the feed-back imped'ances L7, L7" and L8 respectively by means of the switches S1, S1" and S2, damping resistances may alternatel be included in the push-pull input circuit L1, L1", C1 and in the single-phase input circuit (for example in series with the condenser C2) In the last-mentioned case the condenser C1 and the coil Ls may be omitted.

Under certain conditions the said damping resistances, also, may be omitted and the oscillations to be transmitted and the local oscillations for the reception may be generated simultaneously, so that transmission and reception can take place without changing over and, if desired, simultaneously.

Instead of generating the oscillations to be transmitted by means of the mixing systems T and T" they may also be generated, as the case may be, by a couple of high-frequency amplifying systems preceding them.

What I claim is:

a 1. Transceiver apparatus adapted selectively to generate high-frequency oscillations of a pred termined frequency and to mix incoming signals having a carrier of the same frequency with local oscillations, said apparatus comprising a pair of electron discharge tubes each having a cathode, a grid and an anode, first resonant circuit means to apply incoming signals in push-pull relation to the grids of said tubes, second resonant circuit means to derive in push-pull relation intermediate-frequency oscillations from the anodes of the tubes, means to apply local oscillations in parallel relation to the grids of the tubes, for mixing with said incoming signals, means to produce negative damping of said first resonant circuit means causing the generation of said high-frequency oscillations for transmission, and means selectively to actuate said local oscillation applying means and said negative damping producing means.

2. Transceiver apparatus as set forth in claim 1 wherein said means to effect negative damping of said first resonant circuit includes a pair of feedback inductors each interposed between a respective anode of said tubes and said second resonant circuit.

3. lransceiver apparatus adapted selectively to generate high-frequency oscillations of a predetermined frequency and to mix incoming signals having a carrier of the same frequency with local oscillations, said apparatus comprising a pair of electron discharge tubes each having a cathode, a grid and an anode, first resonant circuit means to apply incoming signals in push-pull relation to the grids of said tubes, second resonant circuit means to derive in push-pull relation intermediate-frequency oscillations from the anodes of the tubes, third resonant circuit means to apply local oscillations in parallel relation to the grids of said tubes, and means selectively to effect negative damping of said third resonant circuit means causing the generation of local oscillations and to effect negative damping of said first resonant circuit means causing the generation of said high-frequency oscillation.

4i. Transceiver apparatus adapted selectively to generate high-frequency oscillations of a predetermined frequency and to mix incoming signals having a carrier of the same frequency with local oscillations, said apparatus comprising a pair of electron discharge tubes each having a cathode, a grid and an anode, a first resonant circuit tuned to said predetermined frequency and formed by a centertapped inductance in parallel with a capacitance connected between the grids of said tubes, a second resonant circuit tuned to the intermediate-frequency of said predetermined frequency and said local oscillations and formed by an inductance in parallel with a capacitance coupled between the anodes of said tubes, a third resonant circuit tuned to the frequency of said local oscillations and formed by an inductance connected in series with a capacitance between both cathodes of said tubes and the tap in the inductance of said first resonant circuit, a source of local oscillations, and means selectively to couple said source to said third resonant circuit for mixing with said incoming signals and to effect negative damping of said first resonant circuit causing the generation of high-frequency oscillations for transmission.

5. Transceiver apparatus adapted selectively to generate high-frequency oscillations of a predetermined frequency and to mix incoming signals having a carrier of the same frequency with local oscillations, said apparatus comprising a pair of electron discharge tubes each having a cathode, a grid and an anode, a first resonant circuit tuned to said predetermined frequency and formed by a centertapped inductance in parallel with a capacitor connected between the grids of said tubes, 2. second resonant circuit tuned to the intermediate-frequency of said predetermined frequency and said local oscillations and formed by an inductance in parallel with a capacitance coupled between the anodes of said tubes, a third resonant circuit tuned to the frequency of said local oscillations and formed by an inductance connected in series with a capacitance between both cathodes of said tubes and the tap in the inductance of said first resonant circuit, and means selectively to effect negative damping of said third resonant circuit causing the generation of local oscillations for mixing with said incoming signals and to efiect negative damping of said first resonant circuit causing the generation of high-frequency oscillations for transmission.

6, Transceiver apparatus adapted selectively to generate high-frequency oscillations of a predetermined frequency and to mix incoming signals having a carrier of the same frequency with local oscillations, said apparatus comprising a pair of electron discharge tubes each having a cathode, a grid and an anode, said cathodes being interconnected, a first resonant circuit tuned to said predetermined frequency and formed by a centertapped inductance in parallel with a capacitance connected between the grids of said tubes, first and second feedback inductors, a second resonant circuit tuned to the intermediate frequency of the high-frequency and local oscillations and formed by an inductance in parallel with a pair of series-connected capacitances whose free ends are connected respectively through said first and second feedback inductors to the anodes of said tubes, at third resonant circuit tuned to the frequency of local oscillations and formed by an inductance connected in series with a capacitance between the inter-connected cathodes of said tubes and the tap in the inductance of said first resonant circuit, a capacitor having one end connected to the junction of said series-connected capacitances, a third feedback inductor having one end connected to the junction of said series-connected capacitances, and selective switching means arranged in one position simultaneously to short-circuit said first and second feedback inductors and to connect the other end of said capacitor to said interconnected cathodes, and in another position to connect the other end of said third feedback inductor to said interconnected cathodes.

7. Apparatus as set forth in claim 6, further including a pair of high-frequency chokes interposed between the respective ends of the inductance in the second resonant circuit and the seriesconnected capacitances connected in parallel therewith.

ADELBERT VAN WEEL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,769,920 Gray July 8, 1930 1,935,316 Galt NOV. 14, 1933 1,974,184 Haigis Sept. 18, 1934 2,018,569 Pettengill et al Oct. 22, 1935 2,107,395 Schlesinger Feb. 8, 1938 2,128,422 Lindenblad Aug. 30, 1938 2,205,359 Jensen June 18, 1940 2,285,372 Strutt June 2, 1942 2,296,107 Kimball Sept. 15, 1942 2,434,474 Strutt Jan. 13, 1948 FOREIGN PATENTS Number Country Date 673,968 France Oct. :14, 1929 733,947 France July 19, 1932 

